LT1-LT4 Modifications 1993-97 Gen II Small Block V8

93/94 swap hard start.

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Old Nov 7, 2010 | 05:24 AM
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Default 93/94 swap hard start.

I just finished up swapping the 94 4l60e/harness/computer/etc.. into my 93 formy.

I am having problems with it starting. When I go to start it I let the fuel pump build pressure then I crank the engine, the engine cranks for a little while. I am peddling the throttle slightly it will not even fire if I do not do this.

Related info:

- I do have a cel, but have not pulled the code
- The pcm is tuned for this setup(mostly anyways)
- I am running a 93 throttle body
- Once it fires and runs it runs very good

Oh, I tried switching to a later year throttle body and it would fire quick and easy but it would rev to about 2 grand for a second then die.

If I revved it on startup sometimes it would try to idle but usually failed. IAC problem?

If you have any suggeestions or help I would really appreciate it.

Thanks!
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Old Nov 7, 2010 | 05:02 PM
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ttt
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Old Nov 7, 2010 | 05:15 PM
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I think the problem is not related with your swap, u should check you tps voltage.

check this link: http://www.lt1swap.com/93lt1a4.htm
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Old Nov 7, 2010 | 05:36 PM
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- I am running a 93 throttle body

Problem 1
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Old Nov 7, 2010 | 07:37 PM
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Originally Posted by robsquikz28
- I am running a 93 throttle body

Problem 1
I was told that the IAC was different in the 93 tb to the 94+.. I just kept it on because its the one I know it will run on. Like I mentioned I did try a 94+ tb and it would start, but rev to about 2 grand and then die.
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Old Nov 7, 2010 | 11:05 PM
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There is absolutely no use speculating until you pull the codes.

And what does "mostly anyway" mean in regard to the tune?
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Old Nov 8, 2010 | 12:32 AM
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Originally Posted by RamAir95TA
There is absolutely no use speculating until you pull the codes.

And what does "mostly anyway" mean in regard to the tune?
Well.. it is a canned tune from pcm4less, I had to scale the injectors down for my stockers that are in it for now. It was tuned for 44lb injectors...

Also it is tuned for a 52mm aftermarket throttle body and I am using oem ones to test.

Other than that it is tuned for the 306 cam in a similar setup.

Hopefully I can wake up in time to go fix the brakes and put the exhaust on it so I can take it to oriellys and pull the codes.
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Old Nov 8, 2010 | 06:54 PM
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You need the stock tune back in it pal...
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Old Nov 8, 2010 | 07:06 PM
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Neutral safety switch? Just an idea.......
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Old Nov 8, 2010 | 11:02 PM
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You need the 94+ IAC+housing. I did this swap a while ago and it was straight forward. Sounds like you need a tune more than anything.
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Old Nov 9, 2010 | 01:51 AM
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Originally Posted by NewOrleansLT1
You need the stock tune back in it pal...
Dont have it

Originally Posted by 1badzee
You need the 94+ IAC+housing. I did this swap a while ago and it was straight forward. Sounds like you need a tune more than anything.
I have one in it now.. Its better but it still starts hard. It started great and idled great for a while but now its starting hard.. It idles decent though.. I need to have it tuned and try another IAC possibly.
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Old Nov 9, 2010 | 07:55 AM
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a dealer could put it back to the stock tune, I would think. I'd agree with NewOrleans on this one: you need a stock tune for a stock car.
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Old Nov 9, 2010 | 08:15 AM
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You are chasing a problem that you likely created yourself. You need a stock tune.
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Old Nov 14, 2010 | 03:55 AM
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But.. its not stock.. it just has stock injectors. It has the cc306, -5cc pistons, 2.02/1.60s with slightly worked over heads and IM.

I may have found the issue. I fixed a few vacuum leaks and fired it up with freescan and noticed the coolant temp sensor is not readimg.

Oh and I switched the tb out for one off of a 96
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Old Nov 18, 2010 | 08:28 AM
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The vacuum leak was causing the revving then dying and the coolant sensor caused the hard start. I also had a bad plug wire. Fixed these issues and it runs great!

Last edited by mattcossel29; Nov 18, 2010 at 08:33 AM.
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